/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2005 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.sun.org.apache.xerces.internal.dom;

import com.sun.org.apache.xerces.internal.impl.RevalidationHandler;
import com.sun.org.apache.xerces.internal.parsers.DOMParserImpl;
import com.sun.org.apache.xerces.internal.parsers.DTDConfiguration;
import com.sun.org.apache.xerces.internal.parsers.XIncludeAwareParserConfiguration;
import com.sun.org.apache.xerces.internal.util.XMLChar;
import com.sun.org.apache.xerces.internal.utils.ObjectFactory;
import com.sun.org.apache.xerces.internal.xni.grammars.XMLGrammarDescription;
import com.sun.org.apache.xml.internal.serialize.DOMSerializerImpl;
import org.w3c.dom.DOMException;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;
import org.w3c.dom.ls.LSParser;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSInput;
import org.w3c.dom.ls.LSOutput;
import org.w3c.dom.ls.LSSerializer;

/**
 * The DOMImplementation class is description of a particular
 * implementation of the Document Object Model. As such its data is
 * static, shared by all instances of this implementation.
 * <P>
 * The DOM API requires that it be a real object rather than static
 * methods. However, there's nothing that says it can't be a singleton,
 * so that's how I've implemented it.
 * <P>
 * This particular class, along with CoreDocumentImpl, supports the DOM
 * Core and Load/Save (Experimental). Optional modules are supported by
 * the more complete DOMImplementation class along with DocumentImpl.
 *
 * @xerces.internal
 *
 * @version $Id: CoreDOMImplementationImpl.java,v 1.6 2010-11-01 04:39:37 joehw Exp $
 * @since PR-DOM-Level-1-19980818.
 */
public class CoreDOMImplementationImpl implements DOMImplementation, DOMImplementationLS {
    //
    // Data
    //

    // validators pool
    private static final int SIZE = 2;
    private RevalidationHandler validators[] = new RevalidationHandler[SIZE];

    private RevalidationHandler dtdValidators[] = new RevalidationHandler[SIZE];
    private int freeValidatorIndex = -1;
    private int freeDTDValidatorIndex = -1;
    private int currentSize = SIZE;

    // Document and doctype counter.  Used to assign order to documents and
    // doctypes without owners, on an demand basis.   Used for
    // compareDocumentPosition
    private int docAndDoctypeCounter = 0;

    // static
    /** Dom implementation singleton. */
    static CoreDOMImplementationImpl singleton = new CoreDOMImplementationImpl();

    //
    // Public methods
    //
    /** NON-DOM: Obtain and return the single shared object */
    public static DOMImplementation getDOMImplementation() {
        return singleton;
    }

    //
    // DOMImplementation methods
    //
    /**
     * Test if the DOM implementation supports a specific "feature" --
     * currently meaning language and level thereof.
     *
     * @param feature The package name of the feature to test.
     * In Level 1, supported values are "HTML" and "XML" (case-insensitive).
     * At this writing, com.sun.org.apache.xerces.internal.dom supports only XML.
     *
     * @param version The version number of the feature being tested.
     * This is interpreted as "Version of the DOM API supported for the
     * specified Feature", and in Level 1 should be "1.0"
     *
     * @return true iff this implementation is compatable with the specified
     * feature and version.
     */
    public boolean hasFeature(String feature, String version) {

        boolean anyVersion = version == null || version.length() == 0;

        // check if Xalan implementation is around and if yes report true for supporting
        // XPath API
        // if a plus sign "+" is prepended to any feature name, implementations
        // are considered in which the specified feature may not be directly
        // castable DOMImplementation.getFeature(feature, version). Without a
        // plus, only features whose interfaces are directly castable are considered.
        if ((feature.equalsIgnoreCase("+XPath")) && (anyVersion || version.equals("3.0"))) {
            try {
                Class xpathClass = ObjectFactory.findProviderClass("com.sun.org.apache.xpath.internal.domapi.XPathEvaluatorImpl", true);

                // Check if the DOM XPath implementation implements
                // the interface org.w3c.dom.XPathEvaluator
                Class interfaces[] = xpathClass.getInterfaces();
                for (int i = 0; i < interfaces.length; i++) {
                    if (interfaces[i].getName().equals("org.w3c.dom.xpath.XPathEvaluator")) {
                        return true;
                    }
                }
            } catch (Exception e) {
                return false;
            }
            return true;
        }
        if (feature.startsWith("+")) {
            feature = feature.substring(1);
        }
        return (feature.equalsIgnoreCase("Core") && (anyVersion || version.equals("1.0") || version.equals("2.0") || version.equals("3.0"))) || (feature.equalsIgnoreCase("XML") && (anyVersion || version.equals("1.0") || version.equals("2.0") || version.equals("3.0"))) || (feature.equalsIgnoreCase("LS") && (anyVersion || version.equals("3.0")));
    } // hasFeature(String,String):boolean

    /**
     * Introduced in DOM Level 2. <p>
     *
     * Creates an empty DocumentType node.
     *
     * @param qualifiedName The qualified name of the document type to be created.
     * @param publicID The document type public identifier.
     * @param systemID The document type system identifier.
     * @since WD-DOM-Level-2-19990923
     */
    public DocumentType createDocumentType(String qualifiedName, String publicID, String systemID) {
        // REVISIT: this might allow creation of invalid name for DOCTYPE
        //          xmlns prefix.
        //          also there is no way for a user to turn off error checking.
        checkQName(qualifiedName);
        return new DocumentTypeImpl(null, qualifiedName, publicID, systemID);
    }

    final void checkQName(String qname) {
        int index = qname.indexOf(':');
        int lastIndex = qname.lastIndexOf(':');
        int length = qname.length();

        // it is an error for NCName to have more than one ':'
        // check if it is valid QName [Namespace in XML production 6]
        if (index == 0 || index == length - 1 || lastIndex != index) {
            String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NAMESPACE_ERR", null);
            throw new DOMException(DOMException.NAMESPACE_ERR, msg);
        }
        int start = 0;
        // Namespace in XML production [6]
        if (index > 0) {
            // check that prefix is NCName
            if (!XMLChar.isNCNameStart(qname.charAt(start))) {
                String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INVALID_CHARACTER_ERR", null);
                throw new DOMException(DOMException.INVALID_CHARACTER_ERR, msg);
            }
            for (int i = 1; i < index; i++) {
                if (!XMLChar.isNCName(qname.charAt(i))) {
                    String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INVALID_CHARACTER_ERR", null);
                    throw new DOMException(DOMException.INVALID_CHARACTER_ERR, msg);
                }
            }
            start = index + 1;
        }

        // check local part
        if (!XMLChar.isNCNameStart(qname.charAt(start))) {
            // REVISIT: add qname parameter to the message
            String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INVALID_CHARACTER_ERR", null);
            throw new DOMException(DOMException.INVALID_CHARACTER_ERR, msg);
        }
        for (int i = start + 1; i < length; i++) {
            if (!XMLChar.isNCName(qname.charAt(i))) {
                String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INVALID_CHARACTER_ERR", null);
                throw new DOMException(DOMException.INVALID_CHARACTER_ERR, msg);
            }
        }
    }

    /**
     * Introduced in DOM Level 2. <p>
     *
     * Creates an XML Document object of the specified type with its document
     * element.
     *
     * @param namespaceURI     The namespace URI of the document
     *                         element to create, or null.
     * @param qualifiedName    The qualified name of the document
     *                         element to create.
     * @param doctype          The type of document to be created or null.<p>
     *
     *                         When doctype is not null, its
     *                         Node.ownerDocument attribute is set to
     *                         the document being created.
     * @return Document        A new Document object.
     * @throws DOMException    WRONG_DOCUMENT_ERR: Raised if doctype has
     *                         already been used with a different document.
     * @since WD-DOM-Level-2-19990923
     */
    public Document createDocument(String namespaceURI, String qualifiedName, DocumentType doctype) throws DOMException {
        if (doctype != null && doctype.getOwnerDocument() != null) {
            String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "WRONG_DOCUMENT_ERR", null);
            throw new DOMException(DOMException.WRONG_DOCUMENT_ERR, msg);
        }
        CoreDocumentImpl doc = new CoreDocumentImpl(doctype);
        Element e = doc.createElementNS(namespaceURI, qualifiedName);
        doc.appendChild(e);
        return doc;
    }

    /**
     * DOM Level 3 WD - Experimental.
     */
    public Object getFeature(String feature, String version) {
        if (singleton.hasFeature(feature, version)) {
            if ((feature.equalsIgnoreCase("+XPath"))) {
                try {
                    Class xpathClass = ObjectFactory.findProviderClass("com.sun.org.apache.xpath.internal.domapi.XPathEvaluatorImpl", true);
                    // Check if the DOM XPath implementation implements
                    // the interface org.w3c.dom.XPathEvaluator
                    Class interfaces[] = xpathClass.getInterfaces();
                    for (int i = 0; i < interfaces.length; i++) {
                        if (interfaces[i].getName().equals("org.w3c.dom.xpath.XPathEvaluator")) {
                            return xpathClass.newInstance();
                        }
                    }
                } catch (Exception e) {
                    return null;
                }
            } else {
                return singleton;
            }
        }
        return null;
    }

    // DOM L3 LS

    /**
     * DOM Level 3 LS CR - Experimental.
    * Create a new <code>LSParser</code>. The newly constructed parser may
    * then be configured by means of its <code>DOMConfiguration</code>
    * object, and used to parse documents by means of its <code>parse</code>
    *  method.
    * @param mode  The <code>mode</code> argument is either
    *   <code>MODE_SYNCHRONOUS</code> or <code>MODE_ASYNCHRONOUS</code>, if
    *   <code>mode</code> is <code>MODE_SYNCHRONOUS</code> then the
    *   <code>LSParser</code> that is created will operate in synchronous
    *   mode, if it's <code>MODE_ASYNCHRONOUS</code> then the
    *   <code>LSParser</code> that is created will operate in asynchronous
    *   mode.
    * @param schemaType  An absolute URI representing the type of the schema
    *   language used during the load of a <code>Document</code> using the
    *   newly created <code>LSParser</code>. Note that no lexical checking
    *   is done on the absolute URI. In order to create a
    *   <code>LSParser</code> for any kind of schema types (i.e. the
    *   LSParser will be free to use any schema found), use the value
    *   <code>null</code>.
    * <p ><b>Note:</b>    For W3C XML Schema [<a href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part 1</a>]
    *   , applications must use the value
    *   <code>"http://www.w3.org/2001/XMLSchema"</code>. For XML DTD [<a href='http://www.w3.org/TR/2000/REC-xml-20001006'>XML 1.0</a>],
    *   applications must use the value
    *   <code>"http://www.w3.org/TR/REC-xml"</code>. Other Schema languages
    *   are outside the scope of the W3C and therefore should recommend an
    *   absolute URI in order to use this method.
    * @return  The newly created <code>LSParser</code> object. This
    *   <code>LSParser</code> is either synchronous or asynchronous
    *   depending on the value of the <code>mode</code> argument.
    * <p ><b>Note:</b>    By default, the newly created <code>LSParser</code>
    *    does not contain a <code>DOMErrorHandler</code>, i.e. the value of
    *   the "<a href='http://www.w3.org/TR/2003/WD-DOM-Level-3-Core-20030609/core.html#parameter-error-handler'>
    *   error-handler</a>" configuration parameter is <code>null</code>. However, implementations
    *   may provide a default error handler at creation time. In that case,
    *   the initial value of the <code>"error-handler"</code> configuration
    *   parameter on the new created <code>LSParser</code> contains a
    *   reference to the default error handler.
    * @exception DOMException
    *    NOT_SUPPORTED_ERR: Raised if the requested mode or schema type is
    *   not supported.
     */
    public LSParser createLSParser(short mode, String schemaType) throws DOMException {
        if (mode != DOMImplementationLS.MODE_SYNCHRONOUS || (schemaType != null && !"http://www.w3.org/2001/XMLSchema".equals(schemaType) && !"http://www.w3.org/TR/REC-xml".equals(schemaType))) {
            String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NOT_SUPPORTED_ERR", null);
            throw new DOMException(DOMException.NOT_SUPPORTED_ERR, msg);
        }
        if (schemaType != null && schemaType.equals("http://www.w3.org/TR/REC-xml")) {
            return new DOMParserImpl(new DTDConfiguration(), schemaType);
        } else {
            // create default parser configuration validating against XMLSchemas
            return new DOMParserImpl(new XIncludeAwareParserConfiguration(), schemaType);
        }
    }

    /**
     * DOM Level 3 LS CR - Experimental.
     * Create a new <code>LSSerializer</code> object.
     * @return The newly created <code>LSSerializer</code> object.
     * <p ><b>Note:</b>    By default, the newly created
     * <code>LSSerializer</code> has no <code>DOMErrorHandler</code>,
     * i.e. the value of the <code>"error-handler"</code> configuration
     * parameter is <code>null</code>. However, implementations may
     * provide a default error handler at creation time. In that case, the
     * initial value of the <code>"error-handler"</code> configuration
     * parameter on the new created <code>LSSerializer</code> contains a
     * reference to the default error handler.
     */
    public LSSerializer createLSSerializer() {
        return new DOMSerializerImpl();
    }

    /**
     * DOM Level 3 LS CR - Experimental.
     * Create a new empty input source.
     * @return  The newly created input object.
     */
    public LSInput createLSInput() {
        return new DOMInputImpl();
    }

    //
    // Protected methods
    //
    /** NON-DOM: retrieve validator. */
    synchronized RevalidationHandler getValidator(String schemaType) {
        // REVISIT: implement retrieving DTD validator
        if (schemaType == XMLGrammarDescription.XML_SCHEMA) {
            // create new validator - we should not attempt
            // to restrict the number of validation handlers being
            // requested
            if (freeValidatorIndex < 0) {
                return (RevalidationHandler) (ObjectFactory.newInstance("com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator", ObjectFactory.findClassLoader(), true));
            }
            // return first available validator
            RevalidationHandler val = validators[freeValidatorIndex];
            validators[freeValidatorIndex--] = null;
            return val;
        } else if (schemaType == XMLGrammarDescription.XML_DTD) {
            if (freeDTDValidatorIndex < 0) {
                return (RevalidationHandler) (ObjectFactory.newInstance("com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator", ObjectFactory.findClassLoader(), true));
            }
            // return first available validator
            RevalidationHandler val = dtdValidators[freeDTDValidatorIndex];
            dtdValidators[freeDTDValidatorIndex--] = null;
            return val;
        }
        return null;
    }

    /** NON-DOM: release validator */
    synchronized void releaseValidator(String schemaType, RevalidationHandler validator) {
        // REVISIT: implement support for DTD validators as well
        if (schemaType == XMLGrammarDescription.XML_SCHEMA) {
            ++freeValidatorIndex;
            if (validators.length == freeValidatorIndex) {
                // resize size of the validators
                currentSize += SIZE;
                RevalidationHandler newarray[] = new RevalidationHandler[currentSize];
                System.arraycopy(validators, 0, newarray, 0, validators.length);
                validators = newarray;
            }
            validators[freeValidatorIndex] = validator;
        } else if (schemaType == XMLGrammarDescription.XML_DTD) {
            ++freeDTDValidatorIndex;
            if (dtdValidators.length == freeDTDValidatorIndex) {
                // resize size of the validators
                currentSize += SIZE;
                RevalidationHandler newarray[] = new RevalidationHandler[currentSize];
                System.arraycopy(dtdValidators, 0, newarray, 0, dtdValidators.length);
                dtdValidators = newarray;
            }
            dtdValidators[freeDTDValidatorIndex] = validator;
        }
    }

    /** NON-DOM:  increment document/doctype counter */
    protected synchronized int assignDocumentNumber() {
        return ++docAndDoctypeCounter;
    }

    /** NON-DOM:  increment document/doctype counter */
    protected synchronized int assignDocTypeNumber() {
        return ++docAndDoctypeCounter;
    }

    /* DOM Level 3 LS CR - Experimental.
     *
     * Create a new empty output destination object where
     * <code>LSOutput.characterStream</code>,
     * <code>LSOutput.byteStream</code>, <code>LSOutput.systemId</code>,
     * <code>LSOutput.encoding</code> are null.
    
     * @return  The newly created output object.
     */
    public LSOutput createLSOutput() {
        return new DOMOutputImpl();
    }

} // class DOMImplementationImpl
